Field of the Invention
The present invention relates to an electrochemical device having an electrode body constituted by a positive electrode, a negative electrode and separators that are wound together, as well as a method of manufacturing such electrochemical device.
Description of the Related Art
There is a demand for lowering the costs of lithium ion capacitors and other new electrochemical devices currently used, in order to create a greater market for these devices. To this end, desirably electrochemical devices use cheaper components and have a structure associated with excellent productivity. In terms of their characteristics, there is also a need for electrochemical devices that are smaller and offer higher capacitance.
One electrochemical device structure consists of a flat-wound electrode body produced by stacking and flat-winding a positive electrode and a negative electrode with a separator in between, and then filling the electrode body in an exterior can together with electrolytic solution. The positive electrode and negative electrode must be joined to a positive-electrode terminal and a negative-electrode terminal, respectively, which are provided on the exterior can.
For example, a secondary battery having a flat-wound electrode body structure, as well as a positive-electrode terminal and a negative-electrode terminal connected to both ends of the winding center axis of the electrode body, respectively, is disclosed in Patent Literature 1. Also, an ultrasonic joining method is disclosed in Patent Literature 2, whereby an ultrasonic horn is sandwiched by two electrode bodies and two current collector terminals are placed on the outer sides of the electrode bodies, with the current collector terminals gripped by an ultrasonic anvil and joined to the electrode bodies, respectively, by means of ultrasonic waves.